Data from: An appraisal of the enzyme stability-activity trade-off

A longstanding idea in evolutionary physiology is that an enzyme cannot jointly optimize performance at both high and low temperatures due to a trade-off between stability and activity. Although a stability-activity trade-off has been observed for well-characterized examples, such a trade-off is not imposed by any physical chemical constraint. To better understand the pervasiveness of this trade-off, I investigated the stability-activity relationship for comparative biochemical studies of purified orthologous enzymes identified by a literature search. The nature of this relationship varied greatly among studies. Notably, studies of enzymes with low mean synonymous nucleotide sequence divergence were less likely to exhibit the predicted negative correlation between stability and activity. Similarly, a survey of directed evolution investigations of the stability-activity relationship indicated that these traits are often uncoupled among nearly identical yet phenotypically divergent enzymes. This suggests that the presumptive trade-off often reported for investigations of enzymes with high mean sequence divergence may in some cases instead be a consequence of the degeneration over time of enzyme function in unselected environments, rather than a direct effect of thermal adaptation. The results caution against the general assertion of a stability-activity trade-off during enzyme adaptation.

进化生理学领域的一个经典长期观点指出，由于稳定性与活性之间存在权衡（stability-activity trade-off），酶无法同时在高低温环境下优化其催化性能。尽管已有特征明确的酶学案例证实了该稳定性-活性权衡的存在，但这类权衡并非由任何物理化学约束所强制催生。为深入理解该权衡的普遍性，本研究通过文献检索获取了纯化直系同源酶（purified orthologous enzymes）的比较生化研究数据集，并对其稳定性-活性关系展开了系统性调研。该关系的性质在不同研究中差异显著。值得关注的是，平均同义核苷酸序列分歧度较低的酶相关研究，其观测到稳定性与活性间呈预期负相关的概率更低。类似地，一项针对稳定性-活性关系的定向进化（directed evolution）研究综述显示，在基因型近乎一致但表型存在分化的酶中，这两种性状往往并不耦合。这表明，针对平均序列分歧度较高的酶研究所常报道的推定权衡，在部分情形下或许并非热适应的直接效应，而是酶功能在未经历选择的环境中随时间发生退化的结果。本研究结果警示学界，不应一概而论地断言酶适应过程中必然存在稳定性-活性权衡。